The present invention relates generally to mechanical locks, and more particularly, to shell and core lock assemblies that are removable from a shell lock housing mounted on a wall of an enclosure.
A variety of mechanical locks are known, including locks to secure dwellings, buildings, vehicles, compartments, access hatches, gates, etc. Mechanical locks typically have a rotatable core plug containing a key slot. The insertion of a correctly-bitted key displaces tumbler pins within the lock, thereby allowing the core plug to rotate. The rotation of the core plug actuates an locking bolt or the like that locks or unlocks the structure or enclosure that the lock is a part of. If the key is not a correctly-bitted key, either the key will not be able to fully enter the slot, or the lock will not be allowed to rotate.
xe2x80x9cShell and corexe2x80x9d lock assemblies are known in the art wherein the lock components include separate cylindrical shells and cores that can together be installed with a housing into a wall of an enclosure. Improvements upon such shell and core lock assemblies have made the core and shell removable from the shell housing by the use of a special control key so as to facilitate lock replacement or re-keying. In a removable core lock, the core and shell, including the key plug and tumbler pins, can be removed from the lock using the control key while leaving the remaining lock housing in place. A removable shell and core lock offers the advantage of being able to easily and cheaply change the keying of the lock without removing and replacing the entire lock apparatus by simply removing the shell and core, and then fitting the shell with a new core. Removable core locks may be commonly used in numerous applications where the frequent rekeying of locks is anticipated. The advantages include not only a lesser cost in hardware replacement, but also significant time and labor savings.
An exemplary prior art lock having a removable lock core is disclosed in U.S. Pat. No. 5,070,715 to Smallegan et al. The removable shell and core disclosed in Smallegan is locked inside the shell housing using a compound locking pin which is de-activated by the turning of a control key. During normal lock operation, this locking pin is spring biased into locked position such that it protrudes out of the lock core and into a slot in the shell housing such that the core and shell cannot be axially removed from the housing.
Unfortunately, the prior art removable-core locks commonly have a complicated structure whereby the cores and shells are retained in the shell housing by a series of spring-biased tumbler pins or other movable internal retaining devices comprised of multiple parts. When the core is removed from such locks, these retaining devices have an unfortunate propensity for falling out of the lock or becoming unseated from a desired position. Additionally, normal wear and tear, and contamination such as dirt, often makes removable cores and shells having such spring loaded locking mechanisms difficult to install and remove, or even completely non-functional.
Therefore, there remains a need in the art for a shell and core lock assembly that can be sold and delivered as a unit by a manufacturer for incorporation in enclosures, wherein the core can be easily and efficiently removed and replaced without problems of existing removable core devices and with increased strength and durability.
A shell and core interchangeable lock assembly for use in a shell housing is disclosed. The core comprises a rotatable pin plug and the shell comprises a substantially cylindrical body with a pin chest therein. A mechanism which captures the shell and core within the shell housing comprises an integral retainer ring and lug which is attached to the core. The mechanism allows rapid insertion and removal of the shell and core by the use of a correctly bitted control key. The integral ring and lug construction allows the capturing mechanism to advantageously be controled directly by the rotation of the control key and without multiple spring biasing mechanisms. The mechanism thereby prevents lock operation and core changing by accident or through tampering.
The above and other features, aspects, and advantages of the present invention will be further understood from the following description of the preferred embodiment thereof, taken in conjunction with the accompanying drawings.